Automatic stop eok



ERNEST C. COOK, OF CHICAGO, ILLINOIS.

AUTOMTIC STO? FOR PHONOGRAPI'IS.

Speeificaton of Letters Patent.

Patented. Dec. 9, 1919.

Application filed March 1, 1919. Serial No. 280,040.

,TO all wwm it may Concern Be it known that'I, ERNEST C. COOK, a citizen of the United States, residing at Chicago, in the County of Cook and State of Illinois, have invented a certain new and useful Improvement in Automatic Stops for Phonographs, of which the following is a full, clear, concise, and exact description, reference being had to the accompany ing drawings, formin a part of this specification.

This invention relates to improvements in automatic stops for, phonographs.

The object of the nvention is to provide amanually set, simple and sensitive device for automatically stopping the turning of a phonograph record when the reproducing needle has reached the end of the reproducing portion of the record.

Another object of the inventon is to provide an automatic stop of the type above indicated which may be manufactured at `-comparatively small eXpense in units and readily applied to phonographs now on the market ,and not heretofore equipped with such stops.

In the drawing forming a part of this specification, Figure 1 is a broken view, partly in top plan and partly in horlzontal section of portions of a record-carrylng table, reproducing mechanism, tone arm\ and'automatic stop in connection therewith. Portions of the table and record are broken away in order to more clearly illustrate the automatic stop mechanism. Fig. 2 isan enlarged, Vertical, sectional view taken substantially on theline 2-2 of Fig. 1. And Fig. 3 is a vertical, detail, sectional view taken substantially on the line 3 3 of 1, and illustrating more particularly parts of the automatic stop in end elevation.

In said drawing, 10 denotes the motor board of a phonograph such as is found in those types known as Cabinet phonographs and to the under side of which motor board the motor is generally secured. The rotating table for carrying the record is inclicated at 11, the same being rotatable about thecenter indicatedat 12. AS customary, the table 1 1 is suitably covered on the top thereof with `a layer 13 of felt or other material and the record 14 is applied thereon. The table is formed in the usual man:

ner with a depending Outer annular flange 15,.the lower edge of which is disposed a short distance above the upper, surface of the motor .board 10'. The dotted members 16 indicate conventionally a 'reproducing mechanism and 17 the coperating tone arm, the latter being swiveled about a Vertical aXIS and supported by any suitable means as from the bracket 18 carried by the sleeve member 19 into which the lower enlarged end of 'the tone arm is projected.

In carrying out my invention, I provide a small plate 20 of elongated form as shown most clearly in Fig. 1, the same being adapted to be attached to the motor board 10 by any suitable means such as the screws 21-21. The plate 20 and its associated parts are located in the position shown in Fig. 1 with respect to the table and for the greater part underneath the table. Mounted on the plate 20 is a bell crank lever pivoted at 22. The bell crank lever has a relatively short arm 23 projecting under the fiange `15 of the table and an elongated arm 24,

the ratio of said arms 23 and 24: being ap pronimately as' 1 :3 for the purpose of renderlng the trlpping action extremely sensitive, as hereinafter e plained.

Also mounted on the plate 20 about a' pivot 25 is a cam plate 26 having a handle 27 by which it may be manually set. On the side adjacent the aXiS of the tone arm, the plate 26 is provided with a relatively narrow shoulder as indicated at '127 so located that it will engage with the extreme end 28 of the arm 24 of the bell crank heretofore mentioned. The handle 27 is eX- tended out from under the table so as to be rea'dily accessible to the operator, as will be'understood.` The plate 26 carries a suitthe inner face of the depending flange 15 of the table when the stop is tripped, as hereinafter eX'plained.

The cam plate 26 has attached thereto one end of a tension spring30, the other end of the spring' 30 being attached to a suitable pin 31 carried by the plate 20. As shown most clearly in Fig. 1, a line drawn from the pin 31 to the pin 32 on the cam plate 26 and to which the ends of the spring 30 are attached, passes slightly to one side of the aXiS of rotation of the cam plate 26 so that, when relieved of the restraining influence of the arm 24 of the bell crank, the cam plate 26` will be rotated in a counterclocl wise direction until the clutch element 29 thereon engages the inner face of the flange 15 of the table and stops the latter so that further rotation of the table and record is prevented.

Another Spring 33 is provided having one end thereof attached to said pin 31 and its opposite end Preferably hooked into an opening 34 formed in the bell crank arm 24, Said spring 33 being also under tension in order to hold normally the end 28 of the arm 24 in the position shown in Fig. l. The plate 20 is preferably provided with a small upstanding arm 35 located as shown most clearly in Fgs. 1 and 3 and in which is threaded a set screw 36. The set screw 36 is located in the same plane as the arm 24 of the bell crank and is so adjusted as to limit the outward movement of the arm 24 after it has been tripped from the cam 'the screws 38-38. Said bracket 37 has an arin 39 which is extended first downwardly in a Vertical direction and then outwardly in a horizontal direction as indicated at 40. Pivotally attached to the lower end 40 of the bracket above described, is a right angled lever having a short arm 41 and a longer arm 42. Said lever is pvotally attached to the portion 40 of the bracket by an adjustable friction pivot pin shown most' clearly in Fig. 2, Said friction pivot pin comprising an interiorly threaded sleeve 43 having an annular shoulder 44 at its lower end, a tightening screw 45 and a friction disk 46. The disk 46 is Preferably cupshaped and is engaged by the head of the Screw 45 so as to frictionally press against the lever 41-42 and hold the latter When set against any ordnary pressure. The lever 41-42 is located in the same horizontal plane as the bell crank 23-24 and With the angled portion indicated at 47 so located as to engage and-trip the outer end of'the short arm 23 OI" the bell crank.

AS is well known, the reproducing grooves of the ordinary disk record are placed very Close together, approximately 1/100th of an inch in actual practice, and it is therefore` evident that the automatic stop or trip must be delicately set if it is to eflect the stoppage of the record and `wmotor when the reproducing needle has reached the end of the reproducing grooves. In operating my device,

the cam plate 26 and bell crank 23-24 are l manually set as shown in Fig. 1. The operator then places the reproducing needle indicated at 48 in the last sound reproducing groove or neXt inner blank groove while the parts are stationary and, with the reproducing apparatus and tone arm in this position, the operator manually sets the lever 41-42 so that the shoulder 47 thereof just contacts with the arm 23 of the bell crank. ith the parts thus set, the record is played in the usual manner by moving the reproducing mechanism to the outer edge of the record and placing the.

needle in the grooves and releasing the table by the usual manually Operated brake device (not shown); As the reproducing mechanism and tone arm follow the record grooves inwardly toward the center of the disk, it is evident that the shoulder 47 of the lever 41-42 will approach the short arm 23 of the bell crank and finally will trip the latter as the needle 48 reaches the last sound reproducing groove. As 'the bell crank 23-24 is stripped and swung in a counterclockwise` direction, the end 28 of the long arm of the bell crank will be disengaged from the shoulder 27 of the cam disk 26 and the' latter will thenbe free for rotation under the influence .of the tension Spring 30, thus throwing the brake element 29 against the fiange 15 of the table and stopping further movement thereof.

By employing the relatively short arm`23 and relatively long arm 24 of the bell crank, it is evident that" I render the device eX- tremely sensitive' since movement of the short arm 23 'for a distance of say 1/100th of an inch Will produce substantially three times that amount of movement at the end 28 of the arm 24. Consequently, if the mechanism is set correctly or even approximately correctly before starting to play the record, the automatic stop will be brought'into effective action substantially instantaneously when the reproducing needle 48 reaches the innermost reproducing sound grooves of the record and will prevent operation of the table and record after the needle has passed beyond the sound reproducing grooves. It is evident that the lever 41-42 is so formed as to permit accurate adjustment thereof manually by the operator and urthermore the parts are so designed and assembled that they may be readily manufactured at comparatively small eXpenSe and the tWo units attached to the motor board and tone arm, respectively, with a minimum amount of labor. The Construction of the stop is also such that it may be applied to all of the disk playing types of phonographs without modification of the latter, thus increasing the utility of the numerous phonographs now on the market not equipped with such automatic Stops.

Although I have herein shown and described what I now consider thepreferred manner of carrying out the invention, the same is merely illustrative and l contemplate all Changes and modifications that come Within the scope of the claim appended hereto.

I Claim: i

An automatic stop for phonograph tables comprising, in combination, a base plate adapted to be attached to a fiXed part of the phonograph, a brake element adapted to en'gage With the rotary phonograph table, an oscillatory plate carrying Said brake element and pVOted on Said base plate and having a stop shoulder and a setting handle, a Spring for actuating Said oscillatory plate to apply said brake element, a bell crank leVer pvoted On the base plate and having' a long arm engageable With Said stop Shoulder to hold the brake noperatve and having a short arm rigid With Said long arm and eXtendng away from the Center of the rotary table, a spring' for yieldingly holdng said long arm of the bell Crank lever engaged With Said stop ShOulder, a bracket adapted to` be Secured to the tone arm, a leVer having a ShOulder for engagng Said short ann of the bell crank leVer to release its long arm from said stop shoulder and having a setting handle, and a pivotal frieto'n joint connecting said shouldered lever With Said bracket and adapted to be turned .by the handle of the former and to Overcome by its frcton the tension of the Spring Which actuates the long arm of the bell crank lever.

In Wtnessthat I claim the foregoing I have hereunto subscribed my name this 13th day of Feb., 1919.

ERNEST C. COOK.

Wtness KARL BAACKES. 

